An audio system may include one or more loudspeakers in a room (or other enclosed sound reflective space) that produce sounds that can be heard at each ear of a user or listener in the room. Typically, a left stereo program audio signal that is driving a loudspeaker that is on the left side of a user may still be heard at the right ear of the user, while a right stereo program audio signal that is driving a right side loudspeaker may be heard at the left ear of the user. In a virtual acoustics environment, however, digital signal processing-based crosstalk cancellation (XTC) techniques may be used to digitally process the left and right stereo program audio signals, before they drive their respective loudspeakers, so as to prevent much of the sound in the left stereo program audio signal from being heard at the right ear of the user, and similarly prevent much of the right stereo program audio signal from being heard at the right ear of the user. This isolation may allow, for example, any arbitrary sound to be reproduced at one ear without bleeding to the other ear. Specifically, by controlling how a program audio signal is reproduced as a sound signal at each ear of the user independently, the hearing impression that the program audio is emanating from a location away from the physical loudspeaker may be achieved (e.g., a virtual loudspeaker/sound source).
In some instances, XTC techniques may use only two loudspeakers (e.g., including two degrees of freedom) to control the sound at each ear of the user separately. XTC techniques may compensate for effects generated by sound that is diffracting around the user's head, by applying what are commonly known as Head Related Transfer Functions (HRTFs) to the audio signals that are driving the loudspeakers so that appropriate (desired or target) ear signals are produced at the left ear and at the right ear. Indeed, in certain instances, for XTC techniques to operate most efficiently, the user may be required to remain within a specified location relative to the loudspeakers within a room or other enclosed space. Should the user move outside the specified location, the virtual acoustics effects may diminish and the audio may appear as emanating from the physical loudspeakers instead of from a desired virtual acoustic source location or direction. It may be useful to provide techniques to improve XTC techniques in virtual acoustics environments.